Pneumatically operated timer

ABSTRACT

A timer for use in delaying the actuation of a pneumatically operated valve in which a pneumatic signal first causes a rack to be moved and teeth on the rack to drive a rotatable speed governor, whereby the speed of movement of the rack, which carries a valve operating member, is controlled to control the time taken for the member to reach a position in which the valve is operated to transmit the signal. Means is provided for restoring the rack to an initial position upon cessation of the pneumatic signal.

United States Patent Hodler 1 June 5, 1973 [54] PNEUMATICALLY OPERATED TIMER Primary Examiner-Henry T. Klinksiek [75] Inventor; Karl Homer Bumkon AG" Swit Attorney-Joseph F. Brisebois and John A. Feketis zerland [73] Assignee: H. Kuhnke Electrokechnik GmbH, [57] ABSTRACT Brunishalde, Switzerland A timer for use in delaying the actuation of a pneu- [22] F'led: Jam 1972 matically operated valve in which a pneumatic signal [21] APPL N0.Z 218,263 first causes a rack to be moved and teeth on the rack to drive a rotatable speed governor, whereby the [30] Foreign Application Priority Data speed of movement of the rack, which carries a valve Jan. 20, 1971 Germany ..P 21 02 441.9 operating member, is controlled to control the time taken for the member to reach a position in which the [52] US. Cl ..251/28, 9l/38 valve is operated to transmit the Signal. Means is [Sl] Int. Cl ..Fl6li 31/12 vided for restoring the rack to an initial position upon [58] Field of Search ..251/25, 28, 9911/7358, cessation of the pneumatic Signal [56] References Cited 10 Claims, 3 Drawing Figures UNITED STATES PATENTS 2,600,777 6/1952 Johnson ..91/38 PNEUMATICALLY OPERATED TIMER This invention relates to a timer for use in actuating a valve which transmits a binary pneumatic signal.

Binary pneumatic signals are signals produced by pneumatic pressure which transmit informationconsisting of two distinct kinds or values. Most frequently the two distinct values are zero pressure and a predetermined pressure, e.g. a pressure in excess of atmospheric. The presence of the predetermined pressure value in a pneumatic line usually serves to initiate a process, for example opening a door, or switching on a machine. Frequently a plurality of these processes are initiated by such a signal and it is necessary for the processes to be initiated at different times and/or to last for different periods of time. So called timers are employed for this purpose to transmit a pneumatic signal after a predetermined time or to limit the transmission of the signal to a predetermined time duration. These operations are achieved by using a valve for transmitting the pneumatic signal which is controlled so that either the transmission of the signal is effected after a predetermined time or for a predetermined time duration.

The present invention relates to such a timer which is suitable for operating a valve for transmitting a binary pneumatic pressure signal.

According to the present invention there is provided a timer for use in actuating a valve which transmits a binary pneumatic pressure signal, including drive means operable by a pneumatic signal, a rack movable longitudinally under the control of the drive means, teeth on the rack, a gear drive in engagement with the teeth, a rotatable speed governor, a first valve operating member mounted on and movable with the rack, a second valve operating member positioned for engagement with the first member, the speed governor being in engagement with the gear drive to control the speed of movement of the rack and the first member being movable to a position in which it is in engagement with the second member, thereby to actuate the valve to transmit the signal, and means for restoring the rack to an initial position upon cessation of a pneumatic signal.

Such an arrangement provides an advantageous construction which is simple to manufacture.

The moving parts of the mechanism comprise the pneumatically operated drive means, the rack and the rotatable speed governor. In a preferred embodiment the rotatable speed governor is a balance wheel which serves to maintain the speed of movement of the rack constant. The first valve operating member on the rack constant. The first valve operating member on the rack engages the second member for operating the valve after a time which is adjustable. In so doing the valve is actuated and the transmission of the pneumatic signal is either initiated or interrupted. In the first case a time delayed transmission of the signal is'achieved and in the second case the effective time duration of the pneumatic signal is limited.

A particularly simple embodiment of the invention is possible if the pneumatically operated drive means includes a piston which acts against a restoring spring.

The operation of the valve can be effected directly mechanically or by means of an auxiliary force, e.g. a compressed air auxiliary force. In this case the first valve operating member is a baffle plate and the second member for operating the valve is a nozzle for an auxiliary stream of air to which a control device for the valve, eg a piston in a cylinder, is connected. If the baffle plate approaches the nozzle and thus shuts the latter, the pressure of the auxiliary air stream in the line to the nozzle so increases that the control device for the valve is actuated. In order to avoid the need for any special line for the auxiliary air stream, the source of the auxiliary air stream is the line for the pneumatic signal.

An embodiment of the invention will now be described in more detail, by which of example, with reference to the accompanying drawings in which:

FIG. 1 is a schematic diagram illustrating the relationship between parts of a timer and valve arrangement with the pneumatic circuit,

FIG. 2 shows a diagrammatic front elevation of a device for adjusting and indicating the switch time, and

FIG. 3 is a modification of the arrangement of FIG. 1.

A pneumatic signal is fed to an input showing at E. Should it be necessary to accommodate large fluctuations in the pressure of the signal, a pressure regulator 2 is provided in the line between the input E anda pneumatically operated drive means 1. In the particular embodiment, this drive means 1 comprises a cylinder containing a piston which is operatively movable against a restoring spring 12. In place of this drive device, however, a diaphragm, for example a corrugated tube diaphragm or other suitable pneumatically operated means, can be used. The pneumatically operated drive means moves a rack 3 longitudinally. In the particular embodiment this is effected in the most simple manner by making the rack 3 as an extension of the rod of the piston. The rack 3 has teeth 25 which engage a pinion 4 of a gear train arranged in a housing 5. The gear train acts upon a rotatable speed governor in the form of a balance wheel 6. A free wheel coupling 13 is connected in the gear train between the pinion 4 and the balance wheel 6, which coupling releases the drive connection from the balance wheel upon a restoring movement of the rack. Upon the appearance of a pneumatic signal at the input E, the drive means 1 is operated to cause the piston rod and the rack 3 to be moved towards the left, as seen in FIG. 1. The speed of this movement is controlled by the balance wheel 6, so that it is at a constant value.

The pneumatic signal is further fed, at the same time, to a valve 7 to be transmitted onwards to an output A and, via a throttle 8, to a nozzle 9. This nozzle 9 constitutes a valve operating member and is mounted on a holder 16. The holder 16 has, at its lower end, a bore with a screw thread through which a spindle 15, having a suitable cooperating thread, extends. By means of a slide (not shown) the holder 16 is held in a vertical position. The spindle 15 is rotatable by means of a rotatable knob 14 arranged on the front of the equipment. From the pneumatic line between the input End the nozzle 9 there is a branch line to a pneumatically operated control device for the valve 7. The valve 7 may, for example, have a displaceable control piston which determines the different required connections which it can provide. On one side the piston of the control device for the valve 7 is acted upon by a spring 11 under tension, whilst on the other side it is acted upon by the pressure in the line between the input E and the nozzle 9.

A baffle plate 10, which constitutes a second valve operating member, is movable in a direction corresponding to that in which gas is emitted from the nozzle 9, and is mounted at the righthand end of the rack 3, as seen in FIG. 1. Upon the approach of the baffle plate to the nozzle 9 with movement of the rack 3, the nozzle 9 is closed and the pressure in the pneumatic line, which is practically negligible when the nozzle 9 is open, increases to the pressure of the pneumatic signal fed to the input E.

The mode of operation of the device is as follows:

When a pneumatic signal is applied to the input E, the piston in the pneumatic drive means 1, moves at a constant speed to the left under the influence of the speed control mechanism 5. The baffle plate 10 then closes the nozzle 9, following the expiry of a predetermined delay time. The pressure of the pneumatic signal in the pneumatic line to the nozzle 9 is thereby caused to reach a maximum, resulting in the actuation of the valve 7. Whilst, before the valve is actuated, the output A of the valve is connected to a pressure release connection R, the actuation of the valve 7 results in a connection being made between the input E for the pneumatic signal and the output A of the valve, so that the pneumatic signal is transmitted from the input E to the output A.

So long as a pneumatic signal exists at the input E, the timer mechanism remains actuated in the way described. Upon the removal of the pneumatic signal from the input, the valve 7 is released, under the influence of the spring 11, and the pneumatic signal pressure present at the output A is released via the connection R. The restoring action of the spring 12 brings the piston and the rack 3 back into their starting positions. The free wheel coupling 13 incorporated in the delay mechanism 5 enables this return to be rapid.

The timer is now ready to be operated again.

If on the other hand the pneumatic signal is to be transmitted for a predetermined period of time this can be achieved by modifying the way in which the valve 7 is operated. The operation of the valve 7 is so modified that a connection is provided by the valve between the input E and the output A before the valve is actuated by a pressure increase at the nozzle 9 and the output A is connected to the connection R to release the pressure.

An indicator device, shown in FIG. 2, is able to indicate, not only the adjustable time interval before the valve 7 is actuated, but also the period of time for which a pneumatic signal is transmitted. For this purpose a gear wheel 17 is provided on the threaded spindle 15 which moves the holder 16 for the nozzle 9. The spindle 15 is rotated by the knob 14, thereby rotating the gear wheel 17 and a disc 18. This disc 18 bears a mark 19 which moves past an adjacent scale (see FIG. 2) located on a front plate 20. The position of the mark 19 with respect to the scale is related to the location of the nozzle 9 and thus is able to indicate the adjustable time interval which must elapse before the valve 7 is operated. Furthermore, an indicator 21 is arranged in front of the disc 18 and adjacent the scale on the front plate 20 and is rotatably connected to a spindle 22, having a thread of high pitch, which projects into a bore of the rack 3 which is also provided with a corresponding thread. The longitudinal movement of the rack 3 is thereby translated to a rotary movement of the indicator 21. The indicator 21 thus indicates on the scale on the plate 20 the time of duration of a signal. When the position of the indicator 21 coincides with that of the mark 19, the valve 7 is actuated in the opposite manner to that in which it was actuated in the'previously described manner of operation.

The piston of the drive means for driving the rack 3 can be restored by auxiliary pneumatic pressure instead of by the spring 12. For this purpose a second valve which is operated by the pneumatic signal can be provided. This second valve is arranged. to provide pressure, upon the cessation of the pneumatic signal at the input E, on the left-hand side of the piston of the drive means 1, thereby restoring the piston to its original .position.

Such an arrangement is shown in FIG. 3 in which the pneumatically operated drive means I is a doubleacting cylinder and a valve 23 which is supplied from a source N and is operated against a return spring 24 is connected between the input E and the opposite end of the cylinder of the drive means 1 to that connected to the pressure regulator 2.

If no signal is present at the input E, the spring 24 switches the auxiliary valve 23 to a permanently acting pneumatic pressure from the source N, to whereby the piston of the drive'means 1 and the toothed rack 3 are moved into the starting position.

When a pneumatic signal appears at the input E, the valve 23 is switched against the spring 24 and relieves the piston rod side of the cylinder 1. The piston of the cylinder 1 can now be moved by the signal via the pressure regulator 2 in the manner already described.

When the signal is removed from the input E the piston of the drive means 1 and the rack 3 are restored as a result of pressure applied via the auxiliary valve 23 to the starting position.

I claim:

1. A timer for use in actuating a valve which transmits a binary pneumatic pressure signal, including drive means operable by a pneumatic signal, a rack movable longitudinally under the control of the drive means, teeth on the rack, a gear drive in engagement with the teeth, a rotatable speed governor, a first valve operating member mounted on and movable with the rack, a second valve operating member positioned for engagement with the first member, the speed governor being in engagement with the gear drive to control the speed of movement of the rack and the first member being movable to a position in which it is in engagement with the second member, thereby to actuate the valve to transmit the signal, and means for restoring the rack to an initial position upon cessation of a pneumatic signal.

2. A timer as claimed in claim 1, wherein the first valve operating member mounted on the rack is a baffle plate and the second member for operating the valve is a nozzle, further including a source of auxiliary pressure, and means to feed the auxiliary pressure to the nozzle, the auxiliary pressure, at the same time, acting upon a control device for the valve, wherein, when the nozzle comes into contact with the baffle plate, the,

value of the auxiliary pressure is so increased that the valve is actuated via the control device.

3. A timer as claimed in claim 2 including a throttle in a line connected to a line for transmitting the pneumatic signal, wherein the auxiliary pressure is obtained via the throttle from the line for transmitting the pneumatic signal. r

4. A timer as claimed in claim 2 including a first rotatable threaded spindle, a first indicator device rotatable with the first spindle and indicating the degree of rotation of the said spindle and means for carrying the nozzle in threaded engagement with the said spindle, wherein rotation of the said first spindle causes the nozzle to be displaced, the first indicator giving an indication of the position of the nozzle in relation to the length of the first spindle.

5. A timer as claimed in claim 4 including a scale, wherein the first indicator device indicating the position of the nozzle is a disc having a mark thereon and the disc and the scale are so positioned that the mark on the disc rotates adjacent to the scale.

6. A timer as claimed in claim 5 including a second indicator device and a second threaded rotatable spindle engaging a thread on the rack, the second indicator device being rotatable with the second spindle and indicating the degree of longitudinal movement of the rack and being rotatable coaxially with and in front of the disc for indicating the position of the nozzle adjacent valve, coupled for operation by the pneumatic signal.

and coupled to provide an auxiliary pressure upon the drive means and which, upon the cessation of the pneumatic signal, provides the auxiliary pressure on the drive means to move it in the-opposite direction to that in which it is moved by thepneumatic signal. 

1. A timer for use in actuating a valve which transmits a binary pneumatic pressure signal, including drive means operable by a pneumatic signal, a rack movable longitudinally under the control of the drive means, teeth on the rack, a gear drive in engagement with the teeth, a rotatable speed governor, a first valve operating member mounted on and movable with the rack, a second valve operating member positioned for engagement with the first member, the speed governor being in engagement with the gear drive to control the speed of movement of the rack and the first member being movable to a position in which it is in engagement with the second member, thereby to actuate the valve to transmit the signal, and means for restoring the rack to an initial position upon cessation of a pneumatic signal.
 2. A timer as claimed in claim 1, wherein the first valve operating member mounted on the rack is a baffle plate and the second member for operating the valve is a nozzle, further including a source of auxiliary pressure, and means to feed the auxiliary pressure to the nozzle, the auxiliary pressure, at the same time, acting upon a control device for the valve, wherein, when the nozzle comes into contact with the baffle plate, the value of the auxiliary pressure is so increased that the valve is actuated via the control device.
 3. A timer as claimed in claim 2 including a throttle in a line connected to a line for transmitting the pneumatic signal, wherein the auxiliary pressure is obtained via the throttle from the line for transmitting the pneumatic signal.
 4. A timer as claimed in claim 2 including a first rotatable threaded spindle, a first indicator device rotatable with the first spindle and indicating the degree of rotation of the said spindle and means for carrying the nozzle in threaded engagement with the said spindle, wherein rotation of the said first spindle causes the nozzle to be displaced, the first indicator giving an indication of the position of the nozzle in relation to the length of the first spindle.
 5. A timer as claimed in claim 4 including a scale, wherein the first indicator device indicating the position of the nozzle is a disc having a mark thereon and the disc and the scale are so positioned that the mark on the disc rotates adjacent to the scale.
 6. A timer as claimed in claim 5 including a second indicator device and a second threaded rotatable spindle engaging a thread on the rack, the second indicator device being rotatable with the second spindle and indicating the degree of longitudinal movement of the rack and being rotatable coaxially with and in front of the disc for indicating the position of the nozzle adjacent the scale.
 7. A timer as claimed in claim 1 including a free wheel coupling in the drive for the rotatable speed governor which enables the restoring movement of the rack to be made freely.
 8. A timer as claimeD in claim 1 wherein the drive means includes a piston in a cylinder.
 9. A timer as claimed in claim 1 including a spring arranged to restore the rack to its initial position upon the cessation of the pneumatic signal.
 10. A timer as claimed in claim 1 including a second valve, coupled for operation by the pneumatic signal and coupled to provide an auxiliary pressure upon the drive means and which, upon the cessation of the pneumatic signal, provides the auxiliary pressure on the drive means to move it in the opposite direction to that in which it is moved by the pneumatic signal. 